[PATCH v2 1/2] rng: Add iProc RNG200 driver

Peter Robinson pbrobinson at gmail.com
Mon Dec 28 16:55:45 CET 2020


On Tue, Dec 15, 2020 at 9:49 AM <matthias.bgg at kernel.org> wrote:
>
> From: Matthias Brugger <mbrugger at suse.com>
>
> Add support for random number generator RNG200.
> This is for example found on RPi4.
>
> Signed-off-by: Matthias Brugger <mbrugger at suse.com>
Tested-by: Peter Robinson <pbrobinson at gmail.com>

Tested on a RPi4 class device

> ---
>
> Changes in v2: None
>
>  drivers/rng/Kconfig        |   6 ++
>  drivers/rng/Makefile       |   1 +
>  drivers/rng/iproc_rng200.c | 186 +++++++++++++++++++++++++++++++++++++
>  3 files changed, 193 insertions(+)
>  create mode 100644 drivers/rng/iproc_rng200.c
>
> diff --git a/drivers/rng/Kconfig b/drivers/rng/Kconfig
> index 11001c8ae7..94915d45b3 100644
> --- a/drivers/rng/Kconfig
> +++ b/drivers/rng/Kconfig
> @@ -46,4 +46,10 @@ config RNG_ROCKCHIP
>           Enable random number generator for rockchip.This driver is
>           support rng module of crypto v1 and crypto v2.
>
> +config RNG_IPROC200
> +       bool "Broadcom iProc RNG200 random number generator"
> +       depends on DM_RNG
> +       default n
> +       help
> +         Enable random number generator for RPI4.
>  endif
> diff --git a/drivers/rng/Makefile b/drivers/rng/Makefile
> index 8953406882..39f7ee3f03 100644
> --- a/drivers/rng/Makefile
> +++ b/drivers/rng/Makefile
> @@ -9,3 +9,4 @@ obj-$(CONFIG_RNG_SANDBOX) += sandbox_rng.o
>  obj-$(CONFIG_RNG_MSM) += msm_rng.o
>  obj-$(CONFIG_RNG_STM32MP1) += stm32mp1_rng.o
>  obj-$(CONFIG_RNG_ROCKCHIP) += rockchip_rng.o
> +obj-$(CONFIG_RNG_IPROC200) += iproc_rng200.o
> diff --git a/drivers/rng/iproc_rng200.c b/drivers/rng/iproc_rng200.c
> new file mode 100644
> index 0000000000..1063f43953
> --- /dev/null
> +++ b/drivers/rng/iproc_rng200.c
> @@ -0,0 +1,186 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * Copyright 2020, Matthias Brugger <mbrugger at suse.com>
> + *
> + * Driver for Raspberry Pi hardware random number generator
> + */
> +
> +#include <common.h>
> +#include <dm.h>
> +#include <linux/delay.h>
> +#include <rng.h>
> +#include <asm/io.h>
> +
> +#define usleep_range(a, b) udelay((b))
> +
> +#define RNG_CTRL_OFFSET                                        0x00
> +#define RNG_CTRL_RNG_RBGEN_MASK                                0x00001FFF
> +#define RNG_CTRL_RNG_RBGEN_ENABLE                      0x00000001
> +#define RNG_CTRL_RNG_RBGEN_DISABLE                     0x00000000
> +
> +#define RNG_SOFT_RESET_OFFSET                          0x04
> +#define RNG_SOFT_RESET                                 0x00000001
> +
> +#define RBG_SOFT_RESET_OFFSET                          0x08
> +#define RBG_SOFT_RESET                                 0x00000001
> +
> +#define RNG_INT_STATUS_OFFSET                          0x18
> +#define RNG_INT_STATUS_MASTER_FAIL_LOCKOUT_IRQ_MASK    0x80000000
> +#define RNG_INT_STATUS_NIST_FAIL_IRQ_MASK              0x00000020
> +
> +#define RNG_FIFO_DATA_OFFSET                           0x20
> +
> +#define RNG_FIFO_COUNT_OFFSET                          0x24
> +#define RNG_FIFO_COUNT_RNG_FIFO_COUNT_MASK             0x000000FF
> +
> +struct iproc_rng200_platdata {
> +       fdt_addr_t base;
> +};
> +
> +static void iproc_rng200_enable(struct iproc_rng200_platdata *pdata, bool enable)
> +{
> +       fdt_addr_t rng_base = pdata->base;
> +       u32 val;
> +
> +       val = readl(rng_base + RNG_CTRL_OFFSET);
> +       val &= ~RNG_CTRL_RNG_RBGEN_MASK;
> +       if (enable)
> +               val |= RNG_CTRL_RNG_RBGEN_ENABLE;
> +       else
> +               val &= ~RNG_CTRL_RNG_RBGEN_ENABLE;
> +
> +       writel(val, rng_base + RNG_CTRL_OFFSET);
> +
> +}
> +
> +static void iproc_rng200_restart(struct iproc_rng200_platdata *pdata)
> +{
> +       fdt_addr_t rng_base = pdata->base;
> +       u32 val;
> +
> +       iproc_rng200_enable(pdata, false);
> +
> +       /* Clear all interrupt status */
> +       writel(0xFFFFFFFFUL, rng_base + RNG_INT_STATUS_OFFSET);
> +
> +       /* Reset RNG and RBG */
> +       val = readl(rng_base + RBG_SOFT_RESET_OFFSET);
> +       val |= RBG_SOFT_RESET;
> +       writel(val, rng_base + RBG_SOFT_RESET_OFFSET);
> +
> +       val = readl(rng_base + RNG_SOFT_RESET_OFFSET);
> +       val |= RNG_SOFT_RESET;
> +       writel(val, rng_base + RNG_SOFT_RESET_OFFSET);
> +
> +       val = readl(rng_base + RNG_SOFT_RESET_OFFSET);
> +       val &= ~RNG_SOFT_RESET;
> +       writel(val, rng_base + RNG_SOFT_RESET_OFFSET);
> +
> +       val = readl(rng_base + RBG_SOFT_RESET_OFFSET);
> +       val &= ~RBG_SOFT_RESET;
> +       writel(val, rng_base + RBG_SOFT_RESET_OFFSET);
> +
> +       iproc_rng200_enable(pdata, true);
> +}
> +
> +static int iproc_rng200_read(struct udevice *dev, void *data, size_t len)
> +{
> +       struct iproc_rng200_platdata *priv = dev_get_platdata(dev);
> +       char *buf = (char *)data;
> +       u32 num_remaining = len;
> +       u32 status;
> +
> +       #define MAX_RESETS_PER_READ     1
> +       u32 num_resets = 0;
> +
> +       while (num_remaining > 0) {
> +
> +               /* Is RNG sane? If not, reset it. */
> +               status = readl(priv->base + RNG_INT_STATUS_OFFSET);
> +               if ((status & (RNG_INT_STATUS_MASTER_FAIL_LOCKOUT_IRQ_MASK |
> +                       RNG_INT_STATUS_NIST_FAIL_IRQ_MASK)) != 0) {
> +
> +                       if (num_resets >= MAX_RESETS_PER_READ)
> +                               return len - num_remaining;
> +
> +                       iproc_rng200_restart(priv);
> +                       num_resets++;
> +               }
> +
> +               /* Are there any random numbers available? */
> +               if ((readl(priv->base + RNG_FIFO_COUNT_OFFSET) &
> +                               RNG_FIFO_COUNT_RNG_FIFO_COUNT_MASK) > 0) {
> +
> +                       if (num_remaining >= sizeof(u32)) {
> +                               /* Buffer has room to store entire word */
> +                               *(u32 *)buf = readl(priv->base +
> +                                                       RNG_FIFO_DATA_OFFSET);
> +                               buf += sizeof(u32);
> +                               num_remaining -= sizeof(u32);
> +                       } else {
> +                               /* Buffer can only store partial word */
> +                               u32 rnd_number = readl(priv->base +
> +                                                       RNG_FIFO_DATA_OFFSET);
> +                               memcpy(buf, &rnd_number, num_remaining);
> +                               buf += num_remaining;
> +                               num_remaining = 0;
> +                       }
> +
> +               } else {
> +                       /* Can wait, give others chance to run */
> +                       usleep_range(min(num_remaining * 10, 500U), 500);
> +               }
> +       }
> +
> +       return 0;
> +}
> +
> +static int iproc_rng200_probe(struct udevice *dev)
> +{
> +       struct iproc_rng200_platdata *priv = dev_get_platdata(dev);
> +
> +       iproc_rng200_enable(priv, true);
> +
> +       return 0;
> +}
> +
> +static int iproc_rng200_remove(struct udevice *dev)
> +{
> +       struct iproc_rng200_platdata *priv = dev_get_platdata(dev);
> +
> +       iproc_rng200_enable(priv, false);
> +
> +       return 0;
> +}
> +
> +static int iproc_rng200_ofdata_to_platdata(struct udevice *dev)
> +{
> +       struct iproc_rng200_platdata *pdata = dev_get_platdata(dev);
> +
> +       pdata->base = dev_read_addr(dev);
> +       if (!pdata->base)
> +               return -ENODEV;
> +
> +       return 0;
> +}
> +
> +static const struct dm_rng_ops iproc_rng200_ops = {
> +       .read = iproc_rng200_read,
> +};
> +
> +static const struct udevice_id iproc_rng200_rng_match[] = {
> +       { .compatible = "brcm,bcm2711-rng200", },
> +       { .compatible = "brcm,iproc-rng200", },
> +       {},
> +};
> +
> +U_BOOT_DRIVER(iproc_rng200_rng) = {
> +       .name = "iproc_rng200-rng",
> +       .id = UCLASS_RNG,
> +       .of_match = iproc_rng200_rng_match,
> +       .ops = &iproc_rng200_ops,
> +       .probe = iproc_rng200_probe,
> +       .remove = iproc_rng200_remove,
> +       .platdata_auto_alloc_size = sizeof(struct iproc_rng200_platdata),
> +       .ofdata_to_platdata = iproc_rng200_ofdata_to_platdata,
> +};
> --
> 2.29.2
>


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